Add freeze blacklist module and integrate token freeze guards

[GazzyLee]

Summary

Add freeze functionality to bc-forge token contracts so admins can freeze individual addresses or pause all token transfers independently of the existing pause mechanism.

What changed

• Added new crate: contracts/freeze/

  • freeze_address(address)
  • unfreeze_address(address)
  • is_frozen(address) -> bool
  • freeze_all(), unfreeze_all(), is_all_frozen()
  • Persistent storage via FreezeKey::Address(Address) and FreezeKey::All
  • Emitted freeze-related events

• Updated token contract in contracts/token/src/lib.rs

  • Integrated bc-forge-freeze
  • Added TokenError::ContractFrozen and TokenError::AddressFrozen
  • Added ensure_not_frozen() guard
  • Applied freeze checks to:
    • mint
    • batch_mint
    • transfer
    • transfer_from
    • batch_transfer
  • Added on-chain methods:
    • freeze_address
    • unfreeze_address
    • freeze_all
    • unfreeze_all
    • is_frozen

• Updated SDK in sdk/src/client.ts

  • Added client methods:
    • freezeAddress()
    • unfreezeAddress()
    • isFrozen()

• Fixed workspace compile issue in contracts/admin/src/lib.rs

Validation

• cargo check -p bc-forge-freeze -p bc-forge-token completed successfully

Closes #165

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